Semiconductor device and method of manufacturing the same, and electronic apparatus

ABSTRACT

A semiconductor device is provided as a back-illuminated solid-state imaging device. The device is manufactured by bonding a first semiconductor wafer with a pixel array in a half-finished product state and a second semiconductor wafer with a logic circuit in a half-finished product state together, making the first semiconductor wafer into a thin film, electrically connecting the pixel array and the logic circuit, making the pixel array and the logic circuit into a finished product state, and dividing the first semiconductor wafer and the second semiconductor being bonded together into microchips.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/087,695, filed Mar. 31, 2016, which is a continuation of U.S. patentapplication Ser. No. 14/834,010, filed Aug. 24, 2015, now U.S. Pat. No.9,319,569, which is a continuation of U.S. patent application Ser. No.12/722,069, filed Mar. 11, 2010, now U.S. Pat. No. 9,451,131, whichclaims priority to Japanese Patent Application Nos. JP 2009-068582 andJP 2010-012586, filed in the Japan Patent Office on Mar. 19, 2009 andJan. 22, 2010, respectively, the entire disclosures of which are herebyincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a semiconductor device, such as asolid-state imaging device, and a method of manufacturing such asemiconductor device. The present invention also relates to anelectronic apparatus, such as a camera, equipped with the semiconductordevice.

2. Description of the Related Art

Solid-state imaging devices, which have been commonly used, includeamplification-type solid-state imaging devices as typified by MOS imagesensors such as complementary metal oxide semiconductors (CMOSs) andcharge-transfer solid-state imaging devices as typified by chargecoupled device (CCD) image sensors. These solid-state imaging deviceshave been widely used for digital still cameras, digital video cameras,and so on. Furthermore, in recent years, MOS image sensors have beenused for most of solid-state imaging devices mounted on mobile devicessuch as camera cell-phones and PDAs (Personal Digital Assistants)because of their low power voltages, low consumption powers, and so on.

The MOS solid-state imaging device includes a pixel array (pixel region)where a plurality of unit pixels are arranged in a two-dimensionalarray, and a peripheral circuit region. The unit pixel is formed of aphotodiode and a plurality of pixel transistors, serving as aphotoelectric conversion part. The pixel transistors may be three MOStransistors: a transfer transistor, a reset transistor, and anamplification transistor, or may be four in which a selection transistoris further included.

Some of the MOS solid-state imaging devices are those in which asemiconductor chip with a pixel region on which a plurality of pixel isarranged is electrically connected to a semiconductor chip in which alogic circuit for signal processing is formed to form a single device.Various kinds of such a device have been proposed. For example, JapaneseUnexamined Patent Application Publication No. 2006-49361 discloses asemiconductor module where a back-illuminated image sensor chip having amicro-pad for each pixel cell and a signal processing chip, on which asignal processing circuit is formed, having a micro-pad are connected toeach other via a micro-bump. Japanese Unexamined Patent ApplicationPublication No. 2007-13089 discloses a device on which a sensor chip anda signal processing chip are mounted on an interposer (intermediatesubstrate). The sensor chip is a back-illuminated MOS solid-stateimaging device with an imaging pixel section and the signal processingchip is provided with a peripheral circuit performing signal processing.In Japanese Unexamined Patent Application Publication No. 2008-130603,an imaging device includes an image sensor chip, a thin-layer circuitboard, and a logic circuit chip for signal processing. In addition, italso discloses the configuration of the device in which the thin-layercircuit board and the logic circuit chip are electrically connected toeach other. In this case, the thin-layer circuit board is electricallyconnected from the backside of the image sensor chip through athrough-hole-via.

In addition, Japanese Patent No. 4000507 discloses a solid-state imagingdevice provided with a penetration electrode on a solid-state imagingelement supported on a transparent substrate, where the solid-stateimaging element is electrically connected to a flexible circuitsubstrate. Furthermore, Japanese Unexamined Patent ApplicationPublication No. 2003-31785 discloses a back-illuminated solid-stateimaging device provided with an electrode passing through a supportingsubstrate.

As described in Japanese Unexamined Patent Application Publication Nos.2006-49361, 2007-13089, and 2008-130603, various technologies forcombining an image sensor chip with different circuit chips such aslogic circuit have been proposed. In these technologies, any offunctional chips is almost completely built up in advance and thenmounted on a substrate while being allowed to make a connection betweenthe chips by the formation of a connection through hole.

SUMMARY OF THE INVENTION

As is evident from any of the above solid-state imaging devices, thereis an idea of constructing a semiconductor device by making a connectionbetween different microchips using a connection conductor passingthrough a substrate. However, a connection hole has to be formed deeplyin a substrate while being insulated. Thus, it is practically difficultfrom the viewpoints of the processing of a connection hole and the costeffectiveness of a process for embedding a connection conductor.

On the other hand, the formation of a contact hole with a small diameterof about 1 micrometer uses the thinning of an upper chip to the minimum.In this case, however, some complicated steps, such as one for bondingthe upper chip on a supporting substrate, may be desired, which causesan increase in cost. In order to embed the connection conductor in theconnection hole with a high aspect ratio, the connection conductormaterials are limited because it is necessary to use a CVD film withgood coatability, such as tungsten (W), as a connection conductor.

In order to have economical efficiency simply applicable by massproduction, it is desirable to choose such art that the aspect ratio ofthis connecting hole is lowered dramatically so as to form the holeeasily and the hole is processed within a related-art wafermanufacturing process without using special connecting hole processing.

Furthermore, it is desirable to provide the solid-state imaging devicewith a high performance by designing both an imaging region and a logiccircuit for signal processing to sufficiently exert their respectiveperformances.

In addition to the solid-state imaging device, it is also desirable toprovide any of other semiconductor devices having semiconductorintegrated circuits with high performance by designing the circuits tosufficiently exert their respective performances.

The present invention has been made in consideration of theaforementioned desires and intends to provide a solid-state imagingdevice that allows its circuits to sufficiently exert their respectivecapabilities to attain mass productivity and cost reduction.

Also, the present invention intends to provide an electronic apparatus,such as a camera, equipped with the above solid-state imaging device.

According to an embodiment of the present invention, a semiconductordevice is a back-illuminated solid-state imaging device that includesmicrochips prepared by bonding a first semiconductor wafer having apixel array in a half-finished product state (hereinafter, also referredto as a half-finished pixel array) and a second semiconductor waferhaving a logic circuit in a half-finished product state (hereinafter,also referred to as a half-finished logic circuit) together and thencompleting the circuits to make them into microchips. The bonding mayinclude bonding the semiconductor wafers together, thinning the firstsemiconductor wafer, and making an electric connection between the pixelarray and the logic circuit.

In the semiconductor device according to the embodiment of the presentinvention, a pixel array is formed on a microchip part made of a firstsemiconductor wafer and a logic circuit is formed on a microchip part ofa second semiconductor wafer. Thus, the pixel array and the logiccircuit are formed under optimal conditions. Under the optimal processtechnology, the pixel array and the logic circuit that exert sufficientperformance capabilities can be formed.

The second semiconductor wafer with the half-finished logic circuit canalso serve as a substrate supporting the first semiconductor wafer to bethinned. Subsequently, the first semiconductor wafer with thehalf-finished pixel array and the second semiconductor wafer with thehalf-finished logic circuit are bonded together. Finally, the pixelarray in a finished product state and the logic circuit in a finishedproduct state are formed. Therefore, the back-illuminated solid-stateimaging device suitable for mass production and cost reduction can beobtained.

A method of manufacturing a semiconductor device according to anembodiment of the present invention prepares a first semiconductor waferwith a half-finished pixel array and a second semiconductor wafer with ahalf-finished logic circuit. The method includes steps of bonding thefirst semiconductor wafer and the second semiconductor wafer together,thinning the first semiconductor wafer, and electrically connecting thepixel array and the logic circuit together. The method further includessteps of completing the first semiconductor wafer and the secondsemiconductor wafer which are bonded together and cutting them intopieces for the respective microchips. Consequently, the back-illuminatedsolid-state imaging device can be produced.

In the method of manufacturing the semiconductor device according to theembodiment of the present invention, the pixel array is formed on themicrochip part of the first semiconductor wafer and the logic circuit isformed on the microchip part of the second semiconductor wafer. Both thepixel array and the logic circuit can be formed under optimumconditions. In other words, under the optimal process technology, thepixel array and the logic circuit that exert sufficient performancecapabilities can be formed. In addition, the second semiconductor waferwith the half-finished logic circuit can also serve as a substratesupporting the first semiconductor wafer to be thinned. Subsequently,the first semiconductor wafer with the half-finished pixel array and thesecond semiconductor wafer with the half-finished logic circuit arebonded together, and then subjected to the thinning and the electricconnection, followed by completing the wafers and dividing them into therespective microchips. Consequently, it becomes possible to mass-producethe back-illuminated solid-state imaging device. Thus, the sold-stateimaging device can be produced at low cost.

An electronic apparatus according to an embodiment of the presentinvention includes a solid-state imaging device, an optical system thatintroduces incident light into a photodiode in the solid-state imagingdevice, and a signal-processing circuit that processes an output signalfrom the solid-state imaging device. In the electronic apparatus, thesolid-state imaging device is a back-illuminated solid-state imagingdevice that includes microchips prepared by bonding a firstsemiconductor wafer having a half-finished pixel array and a secondsemiconductor wafer having a half-finished logic circuit together andthen completing the circuits to make them into microchips. The bondingmay include bonding the semiconductor wafers together, thinning thefirst semiconductor wafer, and making an electric connection between thepixel array and the logic circuit. As the electronic apparatus of thepresent invention includes the solid-state imaging device of theembodiment of the present invention, the pixel array and the logiccircuit that exert sufficient performance capabilities for thesolid-state imaging device can be formed. In addition, the solid-stateimaging device can be produced at low cost. Thus, the electronicapparatus can be produced at low cost.

According to an embodiment of the present invention, a semiconductordevice includes microchips prepared by bonding a first semiconductorwafer having a half-finished first semiconductor integrated circuit anda second semiconductor wafer having a half-finished second semiconductorintegrated circuit together and then completing the circuits to makethem into microchips. The bonding may include bonding the semiconductorwafers together, thinning the first semiconductor wafer, and making anelectric connection between the first semiconductor integrated circuitand the second semiconductor integrated circuit.

In the semiconductor device according to the embodiment of the presentinvention, a first semiconductor integrated circuit is formed on amicrochip part made of a first semiconductor wafer and a secondsemiconductor integrated circuit is formed on a microchip part of asecond semiconductor wafer. Thus, the first semiconductor integratedcircuit and the second semiconductor integrated circuit are formed underoptimal conditions. Under the optimal process technology, the firstsemiconductor integrated circuit and the second semiconductor integratedcircuit that exert sufficient performance capabilities can be formed.

The second semiconductor wafer with the second semiconductor integratedcircuit can also serve as a substrate supporting the first semiconductorwafer to be thinned. Subsequently, the first semiconductor wafer withthe half-finished first semiconductor integrated circuit and the secondsemiconductor wafer with the half-finished second semiconductorintegrated circuit are bonded together to finally complete thesemiconductor integrated circuits. Therefore, the semiconductor devicesuitable for mass production and cost reduction can be obtained.

A method of manufacturing a semiconductor device according to anembodiment of the present invention prepares a first semiconductor waferwith a half-finished first semiconductor integrated circuit and a secondsemiconductor wafer with a half-finished second semiconductor integratedcircuit. The method includes steps of bonding the first semiconductorwafer and the second semiconductor wafer together, thinning the firstsemiconductor wafer, and electrically connecting the first semiconductorintegrated circuit and the second semiconductor integrated circuittogether. The method further includes steps of completing the firstsemiconductor wafer and the second semiconductor wafer which are bondedtogether and cutting them into pieces for the respective microchips.

In the method of producing the semiconductor device according to theembodiment of the present invention, a first semiconductor integratedcircuit is formed on a microchip part made of a first semiconductorwafer and a second semiconductor integrated circuit is formed on amicrochip part of a second semiconductor wafer. Thus, the firstsemiconductor integrated circuit and the second semiconductor integratedcircuit are formed under optimal conditions. Under the optimal processtechnology, the first semiconductor integrated circuit and the secondsemiconductor integrated circuit that exert sufficient performancecapabilities can be formed.

In addition, the second semiconductor wafer with the half-finishedsecond semiconductor integrated circuit can also serve as a substratesupporting the first semiconductor to be thinned. Subsequently, thefirst semiconductor wafer with the half-finished first semiconductorintegrated circuit and the second semiconductor wafer with thehalf-finished second semiconductor integrated circuit are bondedtogether, and then subjected to the thinning and the electricconnection, followed by completing the wafers and dividing them into therespective microchips. Consequently, it becomes possible to mass-producethe semiconductor device. Thus, the semiconductor device can be producedat low cost.

In the semiconductor device according to any of the embodiments of thepresent invention, the pixel array and the logic circuit that exerttheir respective sufficient performance capabilities are formed in eachmicrochip part. Thus, a high-performance semiconductor device, or aback-illuminated solid-state imaging device, can be provided. Inaddition, the high-performance back-illuminated solid-state imagingdevice with excellent mass productivity and cost effectiveness can beprovided.

In the semiconductor device according to any of the embodiments of thepresent invention, furthermore, the first semiconductor integratedcircuit and the second semiconductor integrated circuit that exert theirrespective sufficient performance capabilities are formed in eachmicrochip part. Therefore, a high-performance semiconductor device canbe provided. In addition, the high-performance semiconductor device withexcellent mass productivity and cost effectiveness can be provided.

In the method of manufacturing the semiconductor device according to anyof the embodiments of the present invention, under the optimal processtechnology, a high-performance semiconductor device, or ahigh-performance back-illuminated solid-state imaging device, providedwith the pixel array and the logic circuit that exert sufficientperformance capabilities can be manufactured. In addition, thehigh-performance back-illuminated solid-state imaging device withexcellent mass productivity and cost effectiveness can be provided.

In the method of manufacturing the semiconductor device according to anyof the embodiments of the present invention, under the optimal processtechnology, a high-performance semiconductor provided with the firstsemiconductor integrated circuit and the second semiconductor integratedcircuit that exert sufficient performance capabilities can bemanufactured. In addition, the high-performance semiconductor devicewith excellent mass productivity and cost effectiveness can be produced.

The electronic apparatus according to the embodiment of the presentinvention includes a high-performance solid-state imaging device with alower production cost. Therefore, an inexpensive and reliable electronicapparatus can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating the configuration of a MOSsolid-state imaging device according to an embodiment of the presentinvention;

FIGS. 2A to 2C are schematic diagrams illustrating the solid-stateimaging device according to the embodiment of the present invention;

FIG. 3 is a schematic diagram illustrating a main part of thesolid-state imaging device according to a first embodiment of thepresent invention;

FIG. 4 is a diagram (first) illustrating an example of a method ofmanufacturing the solid-state imaging device according to the firstembodiment of the present invention;

FIG. 5 is a diagram (second) illustrating the example of the method ofmanufacturing the solid-state imaging device according to the firstembodiment of the present invention;

FIG. 6 is a diagram (third) illustrating the example of the method ofmanufacturing the solid-state imaging device according to the firstembodiment of the present invention;

FIG. 7 is a diagram (fourth) illustrating the example of the method ofmanufacturing the solid-state imaging device according to the firstembodiment of the present invention;

FIG. 8 is a diagram (fifth) illustrating the example of the method ofmanufacturing the solid-state imaging device according to the firstembodiment of the present invention;

FIG. 9 is a diagram (sixth) illustrating the example of the method ofmanufacturing the solid-state imaging device according to the firstembodiment of the present invention;

FIG. 10 is a diagram (seventh) illustrating the example of the method ofmanufacturing the solid-state imaging device according to the firstembodiment of the present invention;

FIG. 11 is a diagram (eighth) illustrating the example of the method ofmanufacturing the solid-state imaging device according to the firstembodiment of the present invention;

FIG. 12 is a diagram (ninth) illustrating the example of the method ofmanufacturing the solid-state imaging device according to the firstembodiment of the present invention;

FIG. 13 is a diagram (tenth) illustrating the example of the method ofmanufacturing the solid-state imaging device according to the firstembodiment of the present invention;

FIG. 14 is a diagram illustrating a solid-state imaging device accordingto a second embodiment of the present invention;

FIG. 15 is a diagram illustrating a solid-state imaging device accordingto a third embodiment of the present invention;

FIG. 16 is a schematic diagram illustrating a main part of a solid-stateimaging device according to a fourth embodiment of the presentinvention;

FIG. 17 is a diagram (first) illustrating the example of the method ofmanufacturing the solid-state imaging device according to the fourthembodiment of the present invention;

FIG. 18 is a diagram (second) illustrating the example of the method ofmanufacturing the solid-state imaging device according to the fourthembodiment of the present invention;

FIG. 19 is a diagram (third) illustrating the example of the method ofmanufacturing the solid-state imaging device according to the fourthembodiment of the present invention;

FIG. 20 is a diagram (fourth) illustrating the example of the method ofmanufacturing the solid-state imaging device according to the fourthembodiment of the present invention;

FIG. 21 is a diagram (fifth) illustrating the example of the method ofmanufacturing the solid-state imaging device according to the fourthembodiment of the present invention;

FIG. 22 is a schematic diagram illustrating a main part of asemiconductor device according to a fifth embodiment of the presentinvention;

FIG. 23 is a diagram (first) illustrating the example of the method ofmanufacturing the semiconductor device according to the fifth embodimentof the present invention;

FIG. 24 is a diagram (second) illustrating the example of the method ofmanufacturing the semiconductor device according to the fifth embodimentof the present invention;

FIG. 25 is a diagram (third) illustrating the example of the method ofmanufacturing the semiconductor device according to the fifth embodimentof the present invention;

FIG. 26 is a diagram (fourth) illustrating the example of the method ofmanufacturing the semiconductor device according to the fifth embodimentof the present invention;

FIG. 27 is a diagram (fifth) illustrating the example of the method ofmanufacturing the semiconductor device according to the fifth embodimentof the present invention;

FIG. 28 is a diagram (sixth) illustrating the example of the method ofmanufacturing the semiconductor device according to the fifth embodimentof the present invention; and

FIG. 29 is a schematic diagram illustrating the configuration of anelectronic apparatus according to a sixth embodiment of the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, the best mode for carrying out the present invention willbe described as embodiments thereof. The embodiments will be describedin the following order:

1. Example of the schematic configuration of MOS solid-state imagingdevice;

2. First embodiment (an example of the configuration of a solid-stateimaging device and the method of manufacturing the solid-state imagingdevice);

3. Second embodiment (an example of the configuration of a solid-stateimaging device);

4. Third embodiment (an example of the configuration of a solid-stateimaging device);

5. Fourth embodiment (an example of the configuration of a solid-stateimaging apparatus and the method of manufacturing the solid-stateimaging device);

6. Fifth embodiment (an example of the configuration of a semiconductordevice and the method of manufacturing the solid-state imaging device);and

7. Sixth embodiment (an example of an electronic apparatus).

1. Example of the Schematic Configuration of MOS Solid-State ImagingDevice

FIG. 1 is a schematic diagram illustrating an exemplary configuration ofa MOS solid-state imaging device, which can be applied to asemiconductor device of any embodiment of the present invention. Theconfiguration of the MOS solid-state imaging device illustrated in FIG.1 is also applied to a solid-state imaging device according to eachembodiment of the present invention. As shown in FIG. 1, the solid-stateimaging device 1 includes a semiconductor substrate 11; a pixel section(so-called pixel array) 3, where a plurality of pixels 2 withphotoelectric conversion parts are regularly placed on the siliconsubstrate 11, and a peripheral circuit section. Each pixel (i.e., unitpixel) 2 includes a photoelectric conversion part such as a photodiodeand a plurality of pixel transistors (so-called MOS transistors). Theplurality of pixel transistors may include, for example, threetransistors: a transfer transistor, a reset transistor, and anamplification transistor. Alternatively, the plurality of pixeltransistors may further include a selection transistor, thus includingfour transistors. The equivalent circuits of the unit pixel is the sameas one typically used, so that the details thereof will be omitted inthe following description. The pixel 2 may be one unit pixel.Alternatively, the pixel 2 may have a shared pixel structure. The sharedpixel structure includes a plurality of photodiodes, a plurality oftransfer transistors, one shared floating diffusion, and each of sharedother pixel transistors. In other words, the shared pixel structureincludes photodiodes and transfer transistors, which constitute theplurality of unit pixels, and each of other shred pixel transistors.

The peripheral circuit section includes a vertical drive circuit 4, acolumn signal processing circuit 5, a horizontal drive circuit 6, anoutput circuit 7, a control circuit 8, and so on.

The control circuit 8 receives an input clock and data for theinstruction of an operation mode and so on and outputs information suchas the internal information of the solid-state imaging device. In otherwords, the control circuit 8 generates signals, such as a clock signaland a control signal to be referenced for driving the vertical drivecircuit 4, the column signal processing circuit 5, the horizontal drivecircuit 6, and so on. Then, the control unit 8 inputs these signals tothe vertical drive circuit 4, the column signal processing circuit 5,the horizontal drive circuit 6, and so on.

The vertical drive circuit 4 includes a shift register or the like anddrives pixels on a line by selecting a pixel-driving line and supplyinga pulse for driving pixels to a selected pixel line-at-a-time. In otherwords, the vertical drive circuit 4 sequentially performs selectivescanning of pixels 2 of the pixel region 3 line-at-a-time in thevertical direction. Then, the vertical drive circuit 4 supplies a pixelsignal to the column signal processing circuit 5. Here, the pixel signalis based on a signal electric charge generated according to the amountof light received on the photoelectric transducer (e.g., photodiode) ofeach pixel 2 through a vertical signal line 9.

In this embodiment, for example, the column signal processing circuit 5may be provided for each column of the pixels 2 and carries out signalprocessing, such as noise removal, of a signal output from each of thepixels 2 on one line. In other words, the column signal processingcircuit 5 performs CDS (correlated double sampling) for removal of afixed pattern noise specific to the pixel 2 and signal processing suchas signal amplification and AD (analogue-to-digital) conversion. Theoutput stage of the column signal processing circuit 5 is connected to ahorizontal selection switch (not shown) which is located between theoutput stage and a horizontal signal line 10.

The horizontal drive circuit 6, which is constructed of a shift resisteror the like, sequentially outputs horizontal scanning pulses, selectingthe respective column signal processing circuits 5 in order to outputpixel signals thereof to the horizontal signal line 10.

The output circuit 7 carries out signal processing of signalssequentially supplied from the respective column signal processingcircuits 5 through the horizontal signal line 10 and then outputs theprocessed signals. Specifically, for example, the output circuit 7 mayonly perform buffering or may perform black level adjustment, columnvariation compensation, various digital signal processing, and so on. Aninput/output terminal 12 carries out an exchange of signals between thedevice and the outside.

FIGS. 2A to 2C are schematic diagrams illustrating a fundamentalconfiguration of a MOS solid-state imaging device according to anembodiment of the present invention. First, a typical MOS solid-stateimaging device 151 will be described with reference to FIG. 2A. Thetypical MOS solid-state imaging device 151 includes a pixel region 153,a control circuit 154, and a logic circuit 155 for signal processing,which are mounted on a single semiconductor chip 152. In general, animage sensor 156 includes the pixel region 153 and the control circuit154. As shown in FIG. 2B, on the other hand, a MOS solid-state imagingdevice 21 according to the embodiment of the present invention includesa pixel region 23 and a control circuit (control region) 124 mounted ona first semiconductor chip section 22 and a logic circuit 25 including asignal processing circuit for signal processing mounted on a secondsemiconductor chip section 26. The first semiconductor chip section 22and the second semiconductor chip section 26 are electrically connectedto each other to form a single semiconductor chip to provide the MOSsolid-state imaging device 21. As shown in FIG. 2C, in a MOS solid-stateimaging device 27 according to another embodiment of the presentinvention, a pixel region 23 is mounted on a first semiconductor chipsection 22. Also, a control circuit 24 and a logic circuit 25 includingsignal processing circuit are mounted on a second semiconductor chipsection 26. The first semiconductor chip section 22 and the secondsemiconductor chip section 26 are electrically connected to each otherto form a single semiconductor chip to provide the MOS solid-stateimaging device 27.

The features of the MOS solid-state imaging devices according to theabove embodiments are found in their manufacturing methods and theirconfigurations based on such methods as described later.

2. First Embodiment Example of Configuration of Solid-State ImagingDevice and Example of Method of Manufacturing the Solid-State ImagingDevice

Referring now to FIG. 3 and FIGS. 4 to 13, a semiconductor device (i.e.,a MOS solid-state imaging device) and a method of manufacturing thesolid-state imaging device will be described.

In the first embodiment, first, as shown in FIG. 4, a half-finishedimage sensor, or an pixel array (hereinafter, also referred to as apixel region) 23, and a control circuit (control region) 24 are formedon a region to be provided as each microchip part of a firstsemiconductor wafer (hereinafter, also referred to as a semiconductorsubstrate) 31. In other words, a photodiode (PD), which acts as aphotoelectric conversion part of each pixel, is formed on a region to beformed as each microchip part of the semiconductor substrate (forexample, a silicon substrate) 31. Then, a source/drain region 33 of eachpixel transistor is formed on a semiconductor well region 32 in thesemiconductor substrate 31. The semiconductor well region 32 is formedby introduction of first-conductivity type (e.g., p-type) impurities andthe source/drain region 33 is formed by introduction ofsecond-conductivity type (e.g., n-type) impurities. The photodiode (PD)and the source/drain region 33 of each pixel transistor are formed byion implantation from the surface of the substrate 31.

The photodiode (PD) includes an n-type semiconductor region 34 and ap-type semiconductor region 35. Here, the p-type semiconductor region 35is on the surface side of the substrate 31. On the surface of thesubstrate 31 forming the pixel, a gate electrode 36 is formed on a gateinsulating layer. Pixel transistors Tr1 and Tr2 are formed by the gateelectrode 36 and the paired source/drain regions 33. In FIG. 4, forsimplifying the explanation, two pixel transistors Tr1 and Tr2 areillustrated on behalf of a plurality of pixel transistors. The pixeltransistor Tr1 adjacent to the photodiode (PD) is equivalent to atransfer transistor and the source/drain region thereof is equivalent toa floating diffusion (FD). The unit pixels 30 are separated from oneanother by isolation regions 38 respectively. The isolation regions 38are formed by LOCOS (Local Oxidation of Silicon), STI (Shallow TrenchIsolation), or using an impurity diffusion layer having a conductivitytype different from that of a diffusion layer formed as a node. LOCOS isa process where the semiconductor substrate 31 is oxidized to form asilicon oxide layer. STI is a process of providing trenches in thesemiconductor substrate 31 and filling the trenches with a silicon oxidelayer.

On the other hand, on the control circuit (control region) 24, MOStransistors that constitute a control circuit are formed on thesemiconductor substrate 31. FIG. 4 illustrates the MOS transistors thatconstitute the control circuit (control region) 24, as represented byMOS transistors Tr3 and Tr4. Each of the MOS transistors Tr3 and Tr4includes an n-type source/drain region 33 and a gate electrode 36 on agate insulating layer.

Subsequently, a first insulating interlayer 39 is formed on the surfaceof the semiconductor substrate 31 and connection holes are then formedin the insulating interlayer 39, followed by the formation of connectionconductors 44 connecting to the desired transistors through theconnection holes. The formation of the connection conductors 44 withdifferent heights may be performed by stacking a first insulation thinlayer 43 a, such as a silicon dioxide film, and a second insulation thinlayer 43 b, such as a silicon nitride film, on the entire surface of thesemiconductor substrate 31 including the upper surfaces of therespective transistors. Here, the second insulation thin layer 43 b actsas an etching stopper in an etching process for providing a contact holeconnected to the gate electrode 36 and source/drain region 33 andafterward filled with a connection conductor 44. The first insulatinginterlayer 39 is formed on the second insulation thin layer 43 b. Then,the connection holes with different depths are selectively formed in thefirst insulating interlayer 39, reaching to the second insulation thinlayer 43 b provided as the etching stopper. Subsequently, additionalconnection holes are formed in the respective portions of the first andsecond insulation thin layers 43 a and 43 b having the same filmthickness by selective etching so that these additional connection holescan be communicated with the forgoing connection holes, respectively.After that, the connection conductor 44 is embedded in each of theresulting connection holes. In the case where the contact hole isprovided without using the etching stopper, the second insulation thinlayer 43 b may not be formed.

Next, a plurality of layers is formed in the insulating interlayer 39 sothat the layers can be connected to the respective connection conductors44. In this example, but not limited to, a multi-wiring layer 41 isformed by the formation of three metal wiring layers 40. The metalwiring layer 40 is formed of a copper (CU) wiring line. In general, eachcopper wiring line is covered with a barrier metal layer that preventsCu from dispersing. Thus, a cap layer, a so-called protective layer 42,of the copper wiring line 40 is formed on the multi-wiring layer 41. Inthe aforementioned steps, the first semiconductor substrate 31 havingthe half-finished pixel region 23 and control circuit 24 is formed.

On the other hand, as shown in FIG. 5, a half-finished logic circuit 25including a signal processing circuit for signal processing is formed ona region to be provided as each of microchip parts on a secondsemiconductor substrate (semiconductor wafer) 45. Furthermore, on ap-type semiconductor well region 46 on the surface side of the secondsemiconductor substrate (for example, the silicon wafer) 45, a pluralityof MOS transistors, which forms a logic circuit, is formed so that theMOS transistors can be separated from each other by isolation regions50, respectively. Here, the plurality of the MOS transistors isrepresented by MOS transistors Tr6, Tr7, and Tr8. Each of the MOStransistors Tr6, Tr7, and Tr8 is formed using a pair of n-typesource/drain regions 47 and a gate electrode 48 formed on a gateinsulation layer. The logic circuit 25 can be constructed of CMOStransistors.

Subsequently, a first insulating interlayer 49 is formed on the surfaceof the semiconductor substrate 45 and connection holes are then formedin the insulating interlayer 49, followed by the formation of connectionconductors 54 connecting to the desired transistors through therespective connection holes. The formation of the connection conductors54 with different heights may be performed by stacking a firstinsulation thin layer 43 a, such as a silicon dioxide film, and a secondinsulation thin layer 43 b, such as a silicon nitride film, are stackedon the entire surface of the semiconductor substrate 45 including theupper surfaces of the respective transistors. Here, the secondinsulation thin layer 43 b acts as an etching stopper.

The first insulating interlayer 49 is formed on the second insulationthin layer 43 b. Then, the connection holes with different depths areselectively formed in the first insulating interlayer 49, reaching tothe second insulation thin layer 43 b provided as an etching stopper.Subsequently, additional connection holes are formed in the respectiveportions of the first and second insulation thin layers 43 a and 43 bhaving the same film thickness by selective etching so that theseadditional connection holes can be communicated with the forgoingconnection holes, respectively. After that, a connection conductor 44 isembedded in each of the resulting connection holes.

On the other hand, at a desired position on the area to be provided aseach of microchip parts, a connection hole is formed from the surface ofthe first insulating interlayer 49 to a predetermined depth position inthe semiconductor substrate 45. Then, a connection conductor 51 forextraction electrode is embedded in the resulting connection hole. Theconnection conductor 51 may be made of copper (Cu), tungsten (W),polysilicon, or the like. Before embedding the connection conductor 51,an insulation layer 52 is formed on the inner wall surface of theconnection hole to insulate the connection conductor 51 from thesemiconductor substrate 45.

Next, a plurality of layers is formed through the insulating interlayer49 so that they can be connected to the respective connection conductors54 and the extraction connection conductor 51. In this example, but notlimited to, a multi-wiring layer 55 is formed by the formation of threemetal wiring layers 53. The metal wiring layer 53 is formed of a copper(CU) wiring line. In a manner similar to one described above, a caplayer, a so-called protective layer 56, of the copper wiring line 53 isformed on the multi-wiring layer 49. In the aforementioned steps, thefirst semiconductor substrate 45 having the half-finished logic circuit25 is formed.

Next, as shown in FIG. 6, the first semiconductor substrate 31 and thesecond semiconductor substrate 45 are bonded together so that theirrespective multi-wiring layers 41 and 55 can be faced with each other.The bonding may be performed using plasma bonding, an adhesive agent, orthe like. In the case of the plasma bonding, as shown in FIG. 7, a layer57, such as a plasma TEOS film, a plasma SiN film, a SiON film (blockfilm), or a SiC film, is formed on the bonding surface of each of thefirst and second semiconductor wafers 31 and 45. The bonding surfaceswith the layers 57 are subjected to a plasma treatment and then placedover one another, followed by being bonded by an annealing treatment.Such bonding processing is preferably performed using a low-temperatureprocess at 400° C. or less. Such a range of the temperature will notaffect on the bonding processing, wiring, or the like. In the case ofthe adhesive agent, as shown in FIG. 8, an adhesive layer 58 is formedon one of the bonding surfaces of the first and second semiconductorwafers 31 and 45 and both the wafers are then placed over one anotherthrough the adhesive layer 58. In this example, the bonding is performedusing the plasma bonding.

Next, as shown in FIG. 9, grinding and polishing are performed from theback side 31 b of the first semiconductor substrate 31 to make the firstsemiconductor substrate 31 into a thin film. The thin-film processing isperformed to close in the photodiode (PD). After the thin-filmprocessing, a p-type semiconductor layer for dark current control isformed on the back side of the photodiode (PD).

For example, the semiconductor substrate 31 with a thickness of about600 μm may be thinned to about 1 to 10 μm, preferably about 1 to 5 μm.The thin-film processing has been commonly performed using a separatelyprepared supporting substrate for bonding them together. In theembodiment, however, the second semiconductor substrate 45 on which thelogic circuit 25 is formed is also used as a supporting substrate tomake the first semiconductor substrate 31 into a thin film. After thethin-film processing, an insulating interlayer 59, such as a silicondioxide film, is formed on the backside of the substrate 31. In theback-illuminated solid-state imaging device, the back side 31 b of thefirst semiconductor substrate 31 serves as a light-incident surface.

Next, as shown in FIG. 10, a connection through-hole 61 is formed in thethin-filmed first semiconductor substrate 31 at a desired position of aregion to be provided as each microchip part. The connectionthrough-hole 61 extends from the back side 31 b to the uppermost layerof the wiring 53 of the second semiconductor substrate 45 through thefirst semiconductor substrate 31. Simultaneously, a connection hole 62is formed near the connection through-hole 61 in the first semiconductorsubstrate 31, extending from the back side 31 b to the first layerwiring 40 on the first semiconductor substrate 31. Each of theconnection through-hole 61 and connection hole 62 may have a contactarea of 1 to 5 μm in diameter. Since the connection through-hole 61 andthe connection hole 62 are formed after making the first semiconductorsubstrate 31 into a thin film, these holes 61 and 62 can be formed asmicropores with a smaller aspect ratio. For example, each of theconnection through-hole 61 and the connection hole 62 may have a contactdepth of about 5 to 15 μm. Subsequently, an insulating layer 63 forelectric insulation with the semiconductor substrate 31 is formed on theinner wall surface of each of the connection through-hole 61 and theconnection hole 62.

At this time, the process for manufacturing a pixel array is incompletebecause the steps of forming an on-chip color filter and an on-chipmicrolens are still untouched.

In addition, both the connection holes 61 and 62 may be processed andformed in the extension of the typical wafer process. In the case of thelogic circuit, the process up to the uppermost layer wiring 53 suitablefor a circuit technology has been completed, but the whole manufacturingprocess has not been completed. Therefore, a decrease in manufacturingcost can be attained.

Next, as shown in FIG. 11, a through-connection conductor 64 and aconnection conductor 65 are embedded in the connection through-hole 61and the connection hole 62, respectively. Each of the through-connectionconductor 64 and the connection conductor 65 may be made of a metal,such as copper (Cu) or tungsten (W). After that, an insulatingprotective layer 66 is formed on the entire back side of the firstsemiconductor substrate 31. The insulating protective layer 66 may bemade of, for example, a SiCN film, a plasma silicon nitride film, or aSiC film.

Next, as shown in FIG. 12, a light-shielding layer 67 is formed on aregion to be shielded from light. In this figure, the light-shieldinglayer 67 is formed above the control circuit 24. Alternatively, it maybe also formed above other pixel transistors. The light-shielding layer67 may be a metal layer such as a tungsten film. The light-shieldinglayer 67 is electrically connected to the semiconductor well region 32having a ground potential and prevented from being in an electricallyfloating state. In addition, since the light-shielding layer 67electrically connected to the semiconductor well region 32 is providedwith the ground potential, the semiconductor well region 32 is preventedfrom being in an electrically floating state. A passivation layer 68 isformed on the whole surface of the light-shielding layer 67 so that itentirely covers the light-shielding layer 67. The passivation layer 68may be, for example, a plasma silicon nitride film or a CVD-SiV film.Subsequently, connection holes 69 are formed in the portions of thepassivation layer 68 and the insulating protective layer 66, whichcorrespond to the through-connection conductor 64 and the connectionconductor 65, respectively. Then, connection wiring 72, an aluminumfilm, is formed on a barrier metal layer 71 on the connection hole 69.The barrier metal layer 71 is formed, for example, by a stacked film ofTi (downside)/TiN (upside). The connection wiring 72 is connected toboth the through-connection conductor 64 and the connection conductor 65through the barrier metal layer 71. The connection wiring 72 is used forconnecting the pixel region 23 and the control circuit 24 to the logiccircuit 25 and serves as an extraction electrode from the upper side, orserves as a so-called electrode pad. Hereinafter, the connection wiring72 is also referred to as an electrode pad.

Therefore, an image sensor constructed of the image region 23 and thecontrol circuit 24 formed on the first semiconductor substrate 31 iselectrically connected to the logic circuit 25 formed on the secondsemiconductor substrate 45 through the connection conductor 65, theelectrode pad 72, and the through-connection conductor 64.

After that, a planarizing layer 73 is formed on these structuralcomponents.

Next, as shown in FIG. 13, red (R), green (G), and blue (B) on-chipcolor filters 74 are formed on the planarizing layer 73, correspondingto the respective pixels, and on-chip microlenses 75 are then formed onthe respective color filters 74. In other words, both the on-chip colorfilters 74 and the on-chip microlenses 75 are formed so that each ofthem corresponds to each unit pixel of the pixel array.

Here, to facilitate understanding of the embodiments of the presentinvention, FIG. 12 is an enlarged cross-sectional diagram illustratingthe configuration of the substrate, but the on-chip color filters 74 andon-chip microlenses 75 are not shown in the figure. Thus, the pitchsizes of the on-chip color filters 74 and the on-chip microlenses 75 arereduced with reference to the pitch size of the unit pixels.

Next, although not illustrated in FIG. 13, the electrode pad 72 isexposed by selectively removing a lens material layer 75 a and theplanarizing layer 73. On the other hand, on the side of the secondsemiconductor substrate 45, the surface of the substrate 45 is groundand polished to expose the surface of the connection conductor 51 thatserves as an extraction electrode. After forming a passivation layer 76on the exposed surface of the connection conductor 51 of the secondsemiconductor substrate 45, an opening 77 corresponding to theconnection conductor 51 is formed in the passivation layer 76. Aspherical electrode bump 78 is formed so that it can be electricallyconnected to the connection conductor 51 through the opening 77 (seeFIG. 3). In the first semiconductor substrate 31, therefore, both thepixel region 23 and the control circuit 24 are brought into a finishedproduct state. In the second semiconductor substrate 45, the logiccircuit 25 is brought into a finished product state.

Subsequently, the resulting product is divided into the respectivemicrochips, thereby obtaining a desired back-illuminated solid-stateimaging device 79 as shown in FIG. 3.

In the solid-state imaging device 79 of the first embodiment, if theelectrode pad 72 is used, the device 79 can be electrically connected toexternal wiring by wire bonding to the electrode pad 72. If theelectrode bump 78 is used, the device 78 can be electrically connectedto external wiring by face-down bonding. The user may choose one of theelectrode pad 72 and the electrode bump 78 according to user's wishes.

In the first embodiment, the sold-state imaging device can be inspectedusing the electrode pad 72 with respect to the semiconductor wafers. Inaddition, the inspection includes two inspection steps, one in the stateof wafer and the other in the final module state after cutting intochips.

According to the solid-state imaging device 79 and the manufacturingmethod thereof according to the first embodiment of the presentinvention, both the pixel region 23 and the control circuit 24 areformed on the microchip part from the first semiconductor substrate 31.In addition, the logic circuit 25 for signal processing is formed on themicrochip part from the second semiconductor substrate 45.

In this way, the functions of the pixel array and the functions of thelogic circuit are assigned on different microchip parts, so thatsuitable processing technologies can be individually applied to thepixel array and the logic circuit. Therefore, the performances of thepixel array and the logic circuit can be efficiently exerted. Thus, ahigh-performance solid-state imaging device can be provided.

In the case of the configuration of the device shown in FIG. 2C, onlythe pixel region 23 for receiving incident light may be formed on theside of the semiconductor chip section 22. Thus, the control circuit 24and the logic circuit 25 can be separately formed on the semiconductorchip section 26. Therefore, processing technologies suitable for therespective functional microchips can be independently selected while thesurface area of the product module can be also reduced.

Since the pixel array and the logic circuit can be mounted incombination using the typical wafer-processing technology, theproduction of the device can be also facilitated.

The first semiconductor substrate 31 having the pixel region 23 and thecontrol circuit 24 in a half-finished state and the second semiconductorsubstrate 45 having the logic circuit 25 in a half-finished state areattached together, followed by making the first semiconductor substrate31 into a thin film. In other words, the second semiconductor substrate45 may be used as a supporting substrate for making the firstsemiconductor substrate 31 into a thin film. Therefore, it becomespossible to reduce the number of structural members and reduce thenumber of manufacturing steps. Furthermore, since the connectionthrough-hole is formed during the thin-film formation, the aspect ratioof the hole can be reduced and the formation of connection holes can beperformed with high accuracy. Furthermore, the through-connectionconductor 61 and the connection conductor 62 are embedded into theconnection through-hole and the connection hole of small aspect ratios.Therefore, the metal materials which can be used may include those withlow coatability, such as copper (Cu), as well as those with highcoatability, such as tungsten (W). In other words, the connectionconductor materials hardly impose restrictions on the device. Thus, thepixel region and the control circuit can be electrically connected tothe logic circuit with high precision. Therefore, it becomes possible tomanufacture a high performance solid-state imaging device with high massproductivity while keeping production costs down.

3. Second Embodiment Example of Configuration of Solid-State ImagingDevice

Referring now to FIG. 14, a solid-state imaging device (i.e., a MOSsolid-state imaging device) according to a second embodiment of thepresent invention will be described. The solid-state imaging device 81according to the second embodiment of the present invention isconstructed in a manner similar to that of the first embodiment, exceptfor the followings: In this embodiment, only the electrode pad 72 on theside of the first semiconductor substrate 31 is formed, while theconnection conductor 51, the insulating layer 52, and the electrode bump78 on the side of the second semiconductor substrate 45 are omitted. Inaddition, a passivation layer 76 is formed on the back side of thesecond semiconductor substrate 45. Other structural components are thesame as those described in the first embodiment. Therefore, thecorresponding structural components are designated by the same referencenumerals as those in FIG. 3 to omit the duplicated explanations thereof.In addition, the manufacture of the solid-stage imaging device 81 isperformed by the same method as that of the first embodiment shown inFIG. 4 to FIG. 13, except for the followings: The method of the presentembodiment does not include the steps of forming the connectionconductor 51, the insulating layer 52, and the electrode bump 78 as wellas the formation of the connection hole desired for forming theconnection conductor 51.

The solid-state imaging device of the second embodiment exerts the sameadvantageous effects as those of the first embodiment because of havingthe similar configuration to that of the first embodiment except for theelectrode bump 78. In the second embodiment, the connection hole, theinsulating layer 62, and the connection conductor 61 are not formed onthe side of the logic circuit in advance. Thus, lower costs can beexpected.

4. Third Embodiment Example of Configuration of Solid-State ImagingDevice

Referring now to FIG. 15, a semiconductor device (i.e., a MOSsolid-state imaging device) according to a third embodiment of thepresent invention will be described.

In the solid-state imaging device 83 of the third embodiment, the pixelregion 23 and the control circuit 24 formed on the side of the firstsemiconductor substrate 31 are electrically connected to the logiccircuit 25 on the side of the second semiconductor substrate 45 throughone through-connection conductor 84 formed in the first semiconductorsubstrate 31.

In other words, a connection through-hole 85 is formed such that itextends from the back side 31 b of the first semiconductor substrate tothe uppermost layer of the wiring 53 of the second semiconductorsubstrate 45 through the first semiconductor substrate 31. In addition,part of the connection through-hole 85 reaches to the uppermost layer ofthe wiring 40 of the first semiconductor substrate 31. After theformation of the insulating layer 63 on the inner wall surface of theconnection through-hole 85, the through-connection conductor 84 isembedded in the connection through-hole 85 to connect the wiring 40 onthe side of the pixel region 23 and the control circuit 24 to the wiring53 on the side of the logic circuit 25. In the above first embodiment,the connection conductor 65 is connected to the first layer of thewiring 40 while the connection conductor 65 serves as a connection end.However, in the second embodiment, the through-connection conductor 84is connected to the uppermost layer of the wiring 40. The respectivelayers of the wiring 40 are connected to one another so that theuppermost layer thereof connected to the through-connection conductor 84will serve as a connection end.

In the present embodiment, the pixel region 23 and the control circuit24 are connected to the logic circuit 25 through one through-connectionconductor 84. Thus, an electrode pad 72 that serves as the uppermostlayer of the connection wiring as described in the first embodiment isnot formed.

Other structural components are the same as those described in the firstembodiment. Therefore, the corresponding structural components aredesignated by the same reference numerals as those in FIG. 3 to omit theduplicated explanations thereof. In addition, the manufacture of thesolid-stage imaging device 83 is performed by the same method as that ofthe first embodiment shown in FIG. 4 to FIG. 13, except for the steps offorming the connection conductor 65 and the electric pad 72 and thesteps of selectively etching the lens material layer 75 a and theplanarizing layer 73.

In the third embodiment, the sold-state imaging device can be inspectedusing the electrode pump from the connection conductor 51.

According to the solid-state imaging device 83 of the third embodiment,the pixel region 23 and the control circuit 24 are electricallyconnected to the logic circuit 25 through one through-connectionconductor 84. In addition, the electrode pad 72 is omitted. Thus, theconfiguration of the device is simplified compared with that of thefirst embodiment. Furthermore, the number of the manufacturing steps canbe reduced. Therefore, a further reduction in manufacturing costs can beattained. In addition, the same effects as those described in the firstembodiment can be exerted.

5. Fourth Embodiment Example of Configuration of Solid-State ImagingDevice and Example of Manufacturing Method Thereof

Referring now to FIG. 16 and FIGS. 17 to 21, a semiconductor device(i.e., a MOS solid-state imaging device) according to a fourthembodiment of the present invention and a manufacturing method thereofwill be described.

In the fourth embodiment, first, as shown in FIG. 17, a half-finishedimage sensor, or a pixel region 23, and a control circuit 24 are formedon a region to be provided as each microchip part of a firstsemiconductor substrate 31. The manufacturing steps in the presentembodiment are the same as those illustrated in FIG. 4 of theaforementioned first embodiment. The same reference numerals as in FIG.4 are used to denote the corresponding or similar portions. Thus,redundant descriptions will be omitted. However, in the presentembodiment, the multi-wiring layer 41 is formed on the firstsemiconductor substrate 31. However, the process is completed at thetime of forming the uppermost layer of the wiring 40. In other words,the process is completed when the uppermost layer of the wiring 40 isexposed. The protective layer 42 shown in FIG. 4 is not formed on theexposed layer.

On the other hand, as shown in FIG. 18, a half-finished logic circuit 25for signal processing circuit is formed on a region to be provided aseach of microchip parts on a second semiconductor substrate 45. Themanufacturing steps in the present embodiment are the same as thoseillustrated in FIG. 5 of the aforementioned first embodiment. The samereference numerals as in FIG. 5 are used to denote the correspondingstructural components. Thus, redundant descriptions will be omitted.However, in the present embodiment, the multi-wiring layer 55 is formedon the second semiconductor substrate 45 and the process is completed atthe time of forming the uppermost layer of the wiring 53. In otherwords, the process is completed when the uppermost layer of the wiring53 is exposed. The protective layer 56 shown in FIG. 5 is not formed onthe exposed layer.

Next, as shown in FIG. 19, the first semiconductor substrate 31 and thesecond semiconductor substrate 45 are bonded together so that theirrespective multi-wiring layers 41 and 55 can be faced with each other,while their wiring 40 and 53 are connected to each other and theirinsulating interlayers 39 and 49 are connected to each other.

In this bonding process, the wiring 40 and 53 are copper (Cu) wiring andthe insulating interlayers 39 and 40 are silicon dioxide films.Furthermore, both the semiconductor substrates 31 and 45 are placed overone another and heated while receiving a predetermined load while theirrespective Cu wirings 40 and 50 are directly touched with each other.Simultaneously, the insulating interlayers 39 and 49 may be connectedwith each other. The heating temperature at this time is, for example,about 300° C., which prevents Cu wiring from being deteriorated.

Next, as shown in FIG. 20, grinding and polishing are performed from theback side 31 b of the first semiconductor substrate 31 to thin the firstsemiconductor substrate 31. The thin-film processing is performed toclose in the photodiode (PD). After the thin-film formation, aninsulating interlayer 59, such as a silicon dioxide film, is formed onthe backside of the substrate 31. Subsequently, a connection hole 88 isformed in the thin-filmed first semiconductor substrate 31. Theconnection hole 88 is located at a desired position in a region to beprovided as each microchip part and extends from the back side 31 b ofthe substrate 31 to the first layer of the wiring 40. An insulatinglayer 63 is formed on the inner wall surface of the connection hole 88.Then, the connection hole 62 and the connection through-hole 61 areformed. The connection trough-hole 61 reaches to the uppermost layer ofthe wiring 53 on the side of the second semiconductor substrate 45.Next, a through-connection conductor 64 and a connection conductor 65are embedded in the connection through-hole 61 and the connection hole62, respectively. After that, an insulating protective layer 66 isformed on the entire surface on the back side 31 b of the firstsemiconductor substrate 31. The manufacturing steps illustrated in FIG.20 are the same as those illustrated in FIGS. 9 to 11. The samereference numerals as in FIGS. 9 to 11 are used to denote thecorresponding structural components. Thus, redundant descriptions willbe omitted.

Next, as shown in FIG. 21, an electronic pad 72 and a light-shieldinglayer 67 are formed on the side of the first semiconductor substrate 31.Here, the electric pad 72 is connected to the connection conductor 62and the through-connection conductor 61. Furthermore, a planarizinglayer 73, an on-chip color filter 74, and an on-chip microlens 74 areformed on the same side. On the other hand, on the side of the secondsemiconductor substrate 45, the back side of the substrate is ground andpolished to expose the connection conductor 51. A passivation layer 76is formed and an electrode bump 78 is then formed on the connectionconductor (see FIG. 16). The manufacturing steps illustrated in FIG. 21are the same as those illustrated in FIG. 13 as described above. Thesame reference numerals as in FIG. 13 are used to denote thecorresponding structural components. Thus, redundant descriptions willbe omitted.

Subsequently, the resulting product is divided into the respectivemicrochips, thereby obtaining a desired back-illuminated solid-stateimaging device 91 as shown in FIG. 16. In this embodiment, theconfiguration of the device illustrated in FIG. 2B is employed.Alternatively, the configuration of the device illustrated in FIG. 2Cmay be employed.

According to the solid-state imaging device 91 and the manufacturingmethod thereof according to the fourth embodiment of the presentinvention, in the step of combining the first semiconductor substrate 31and the second semiconductor substrate 45, simultaneously, the wiring 40and the wiring 53 are directly connected to each other. Thus, the pixelregion 23 and the control circuit 24 are electrically connected to thelogic circuit 25, completing their electrical connection. Therefore, thenumber of the manufacturing steps can be further reduced and a furtherreduction in manufacturing costs can be also attained. In addition, thedevice of the present embodiment exerts the same advantageous effects asthose described in the first embodiment.

6. Fifth Embodiment Example of Configuration of Semiconductor Device andExample of Manufacturing Method Thereof

Referring now to FIG. 22 and FIGS. 23 to 28, a semiconductor device anda manufacturing method thereof in accordance with the fifth embodimentof the present invention will be described. The semiconductor device ofthe present embodiment is a semiconductor device on which a firstsemiconductor integrated circuit and a second semiconductor integratedcircuit are mounted in combination.

In the fifth embodiment, first, as shown in FIG. 23, a half-finishedfirst semiconductor integrated circuit (logic circuit 102 in thisexample) is formed on a region to be provided as each of microchip partson a first semiconductor substrate (semiconductor wafer) 101. In otherwords, on the region to be provided as each of microchip parts on thesemiconductor well region 104 formed in the semiconductor substrate(e.g., silicon substrate) 103, a plurality of MOS transistors Tr11,Tr12, and Tr13 are formed. Each of the MOS transistors Tr11 to Tr13includes a pair of source/drain regions 105 and a gate electrode 106with a gate insulating layer placed therebetween. The MOS transistorsTr11 to Tr13 are separated from one another by the presence of isolationregions 107, respectively. Here, but not limited to, the MOS transistorsare represented by MOS transistors Tr11 to Tr13. The logic circuit 102includes CMOS transistors. Therefore, these MOS transistors may ben-channel MOS transistors or p-channel MOS transistors. Thus, when then-channel MOS transistor is formed, an n-type source/drain region isformed on a p-type semiconductor well region. When a p-channel MOStransistor is formed, a p-type source/drain region is formed in ann-type semiconductor well region.

Furthermore, for example, the first semiconductor integrated circuit maybe a semiconductor memory circuit instead of the logic circuit 102. Inthis case, the logic circuit to be used as a second semiconductorintegrated circuit is subjected to the signal processing of thesemiconductor memory circuit.

Next, a plurality of layers are formed on the conductive substrate 103through an interlayer insulating layer 108. In this example, amulti-wiring layer 111 is formed by laminated three metal wiring layers109. For example, the metal wiring 109 may be made of copper, or Cuwiring. In addition, the respective MOS transistors Tr11 to Tr13 areconnected to one another through the desired first layer of the wiring109 and a connection conductor 112. Furthermore, three layers of thewiring 109 are connected to one another through the connectionconductor. A cap layer, a so-called protective layer 114 which preventsthe copper wiring 109 from being dispersed, is formed on themulti-wiring layer 113.

On the other hand, as shown in FIG. 24, a half-finished secondsemiconductor integrated circuit, a logic circuit 117 is formed in aregion to be provided as each microchip part of the second semiconductorsubstrate (semiconductor wafer) 116. In other words, as shown in FIG.20, on the region to be provided as each of microchip parts on thesemiconductor well region 119 formed in the semiconductor substrate(e.g., silicon substrate) 118, a plurality of n-channel MOS transistorsTr21, Tr22, and Tr23 are formed. Each of the MOS transistors Tr21 toTr23 includes a pair of source/drain regions 121 and a gate electrode122 with a gate insulating layer placed therebetween. The MOStransistors Tr21 to Tr23 are separated from one another by the presenceof isolation regions 123, respectively. Here, but not limited to, theMOS transistors are represented by MOS transistors Tr21 to Tr23. Thelogic circuit 117 includes CMOS transistors. Therefore, these MOStransistors may be n-channel MOS transistors or p-channel MOStransistors. Thus, when the n-channel MOS transistor is formed, ann-type source/drain region is formed on a p-type semiconductor wellregion. When a p-channel MOS transistor is formed, a p-type source/drainregion is formed in an n-type semiconductor well region.

Next, a plurality of layers is formed on the conductive substrate 118through an interlayer insulating layer 124. In this example, amulti-wiring layer 126 is formed by laminated three metal wiring layers125. For example, the metal wiring 125 may be made of copper, or Cuwiring. In addition, the respective MOS transistors Tr21 to Tr23 areconnected to one another through the desired first layer of the wiring125 and a connection conductor 112. Furthermore, three layers of thewiring 125 are connected to one another through the connectionconductor.

On the semiconductor substrate 118, furthermore, at a desired positionon the area to be provided as each of microchip parts, a connection holeis formed from the surface of the first insulating interlayer 124 to apredetermined depth position in the semiconductor substrate 118. Then, aconnection conductor 128 for extraction electrode is embedded in theresulting connection hole. The connection conductor 128 may be made ofcopper (Cu), tungsten (W), polysilicon, or the like. Before embeddingthe connection conductor 128, an insulation layer 129 is formed on theinner wall surface of the connection hole to insulate the connectionconductor 128 from the semiconductor substrate 118. Then, a cap layer, aso-called protective layer 127 which prevent the copper wiring 125 frombeing dispersed, is formed on the multi-wiring layer 126.

Next, as shown in FIG. 25, the first semiconductor substrate 101 and thesecond semiconductor substrate 116 are bonded together so that theirrespective multi-wiring layers 111 and 126 can be faced with each other.Just as in the case with the aforementioned embodiment, the bonding maybe performed using plasma bonding, an adhesive agent, or the like. Inthis example, on the bonding surface of each of the first and secondsemiconductor wafers 101 and 116, a layer 129, such as a plasma TEOSfilm, a plasma SiN film, a SiON film (block film), or a SiC film, isformed and bonded together by plasma bonding.

Next, as shown in FIG. 26, grinding and polishing are performed from theback side of the first semiconductor substrate 101 to thin the firstsemiconductor substrate 101. For example, the semiconductor substrate101 with a thickness of 600 μm may be thinned to about 5 to 10 μm.

Next, as shown in FIG. 27, a connection through-hole 131 is formed inthe thin-filmed first semiconductor substrate 101 at a desired positionof a region to be provided as each microchip part. The connectionthrough-hole 131 extends from the back side 101 b to the uppermost layerof the wiring 125 of the second semiconductor substrate 116 through thefirst semiconductor substrate 101. Simultaneously, a connection hole 132is formed near the connection through-hole 131 in the firstsemiconductor substrate 101, extending from the back side 101 b to afirst layer portion of wiring 109 on the first semiconductor substrate101. Since the connection through-hole 131 and the connection hole 132are formed after making the first semiconductor substrate 101 into athin film, these holes 131 and 132 can be formed as micropores with asmaller aspect ratio. Subsequently, an insulating layer 133 for electricinsulation with the semiconductor substrate 101 is formed on the innerwall surface of each of the connection through-hole 131 and theconnection hole 132.

Next, a through-connection conductor 134 and a connection conductor 135are embedded in the connection through-hole 131 and the connection hole132, respectively. Each of the through-connection conductor 134 and theconnection conductor 135 may be made of a metal, such as copper (Cu) ortungsten (W).

Next, as shown in FIG. 28, connection wiring 136 is formed on the backside of the first semiconductor substrate 101 to make a connectionbetween the through-connection conductor 134 and the connectionconductor 135. The first semiconductor integrated circuit 102 iselectrically connected to the second semiconductor integrated circuit117 through the connection conductor 135, the through-connectionconductor 134, and the connection wiring 136. The connection wiring 136serves as an electrode pad used as an extraction electrode. Aninsulating layer is applied to the surface except for the connectionwiring 136 to form an overcoat layer 139. The overcoat layer 139 may be,for example, a plasma silicon nitride film. On the other hand, on theside of the second semiconductor substrate 116, the surface of thesubstrate 116 is ground to expose the surface of the connectionconductor 128 that serves as an extraction electrode. After forming apassivation layer 137 on the exposed surface of the connection conductor128 of the second semiconductor substrate 116, a spherical electrodebump 138 is formed so that it can be electrically connected to theconnection conductor 128 (see FIG. 22).

Subsequently, the resultant is divided into each chip and semiconductordevice 140 to be shown in FIG. 22 is obtained.

According to the semiconductor device 140 and the manufacturing methodthereof according to the fifth embodiment of the present invention, justas in the case with the aforementioned embodiments, the firstsemiconductor integrated circuit and the second semiconductor integratedcircuit can be independently formed on different microchip parts bytheir optimal process technologies, respectively. Therefore, ahigh-performance semiconductor integrated circuit can be provided. Inaddition, a reduction in manufacturing costs can be attained by bondingand thinning the first and second semiconductor wafers together in ahalf-finished product state, electrically connecting the first andsecond integrated circuits to each other, and dividing the resultingcombination in a completed product state into microchips.

In the fifth embodiment, just as in the case with the fourth embodiment,the first and second semiconductor substrates may be bonded together todirectly connect the wiring layers of multi-layered wiring to eachother. Such a configuration of the device can lead to a decrease innumber of manufacturing steps and a further reduction in manufacturingcosts.

Although the solid-state imaging device according to any of the aboveembodiments uses electrons as signal electric charges, a p-type as afirst-conductivity type, and an n-type as a second-conductivity type, itmay be also applied to one using electron holes as signal electroniccharges. In this case, the conductivity types of the semiconductorsubstrates, semiconductor well regions, or semiconductor regions arereversed. Thus, the n-type is provided as the first-conductivity typeand the p-type is provided as the second-conductivity type.

In the solid-state imaging device according to any of the aboveembodiments, the first semiconductor chip section 22 may have athickness smaller than the thickness of the second semiconductor chipsection 26.

7. Sixth Embodiment Example of Configuration of Electronic Apparatus

The solid-state imaging devices according to the embodiments of thepresent invention can be applied to electronic apparatuses includingcamera systems such as digital cameras and video cameras, cellularphones with imaging functions, other apparatuses with imaging functions,and so on.

FIG. 29 illustrates the configuration of a camera as an exemplaryelectronic apparatus according to the sixth embodiment of the presentinvention. An example of the camera according to the present embodimentis a video camera which can shoot a still picture or video. The camera141 of the present embodiment includes a solid-state imaging device 142,an optical system 143 that introduces incident light into aphotoreceptor of the solid-state imaging device 142, and a shutterdevice 144. Furthermore, the camera 141 includes a drive circuit 145 fordriving the solid-state imaging device 142 and a signal processingcircuit 146 for processing an output signal from the solid-state imagingdevice 142.

The solid-state imaging device 142 is any of the solid-state imagingdevices of the aforementioned embodiments. The optical system (opticallens) 143 carries out image formation of image light (incident light)from a photographic subject onto an imaging surface of the solid-stateimaging device 142. Therefore, signal electric charges are accumulatedin the solid-state imaging device 142 for a given period of time. Theoptical system 143 may be an optical lens system constructed of aplurality of optical lenses. The shutter device 144 controls a period oflight irradiation on the solid-state imaging device 142 and a period oflight shielding. The drive circuit 145 supplies drive signals forcontrolling the transfer operation of the solid-state imaging device 142and the shutter operation of the shutter device 144. The driving signals(timing signals) supplied from the drive circuit 145 allow thesolid-state imaging device 142 to transmit signals. Thesignal-processing circuit 146 performs various kinds of signalprocessing. Video signals subjected to the signal processing are storedin a storage medium such as a memory or outputted to a monitor.

The electronic apparatus, such as a camera, according to the sixthembodiment of the present invention includes a high-performancesolid-state imaging device 142 with a lower production cost. Therefore,an inexpensive and reliable electronic apparatus can be provided.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

What is claimed is:
 1. An imaging device, comprising: a firstsemiconductor substrate having a light-incident side and including apixel section, the pixel section including a plurality of photodiodesand at least one of a plurality of transfer transistors, resettransistors, and amplification transistors; a second semiconductorsubstrate having at least a portion of a signal processing circuit,wherein the first semiconductor substrate and the second semiconductorsubstrate are bonded to each other; a first multi-wiring layer formed ata side opposite to the light-incident side of the first semiconductorsubstrate, wherein the first multi-wiring layer is electricallyconnected to the pixel section; a second multi-wiring layer formed at afirst side of the second semiconductor substrate, wherein the sideopposite to the light-incident side of the first semiconductor substrateand the first side of the second semiconductor substrate face eachother, and wherein the signal processing circuit includes at least aplurality of wirings of the second multi-wiring layer and a plurality oftransistors; and an electrode disposed in a peripheral section otherthan the pixel section, wherein the electrode is coupled to a wiring inthe second multi-wiring layer such that the wiring in the secondmulti-wiring layer is electrically connected to an external wiring,wherein, the first multi-wiring layer includes a plurality of firstconnection portions that directly connect to a plurality of secondconnection portions in the second multi-wiring layer, and at least oneconnection portion of the plurality of first connection portions or theplurality of second connection portions is disposed in an areahorizontally located between the pixel section and the electrode.
 2. Theimaging device of claim 1, further comprising: an insulating layerbetween the electrode and the light-incident side of the firstsemiconductor substrate.
 3. The imaging device of claim 1, furthercomprising: a through-connection conductor coupled to the electrode. 4.The imaging device of claim 3, further comprising: a connectionthrough-hole in which the through-connection conductor is disposed. 5.The imaging device of claim 4, further comprising: a second insulatinglayer disposed on at least a part of an inner wall of the connectionthrough-hole.
 6. The imaging device of claim 3, wherein thethrough-connection conductor connects at least a lower wiring layer ofthe first multi-wiring layer and at least an upper wiring layer of thesecond multi-wiring layer.
 7. The imaging device of claim 6, wherein thelower wiring layer of the first multi-wiring layer is connected to otherwiring layers in the first multi-wiring layer.
 8. The imaging device ofclaim 3, wherein the through-connection conductor connects a lowestwiring layer of the first multi-wiring layer and an uppermost wiringlayer of the second multi-wiring layer.
 9. The imaging device of claim3, wherein the through-connection conductor connects the pixel sectionand a logic circuit.
 10. The imaging device of claim 3, wherein theelectrode is connected to the through-connection conductor and anotherconnection conductor.
 11. The imaging device of claim 3, furtherincluding a micro-lens formed at the light-incident side of the firstsemiconductor substrate, wherein the through-connection conductor isformed in a predetermined area not corresponding to the micro-lens onthe light-incident side of the first semiconductor substrate.
 12. Theimaging device of claim 1, wherein the first semiconductor substrate andthe second semiconductor substrate are bonded to each other so that thefirst multi-wiring layer and the second multi-wiring layer face eachother.
 13. The imaging device of claim 1, wherein a thickness of thefirst semiconductor substrate is less than a thickness of the secondsemiconductor substrate.
 14. The imaging device of claim 1, furtherincluding a color filter formed at the light-incident side of the firstsemiconductor substrate.
 15. The imaging device of claim 1, wherein theplurality of first connection portions and the plurality of secondconnection portions are copper wirings.
 16. The imaging device of claim1, wherein the first semiconductor substrate and the secondsemiconductor substrate are bonded by using a plasma bonding.
 17. Theimaging device of claim 1, wherein at least one of a plasma TEOS film, aplasma SiN film, a SiON film, or a SiC film is formed on a bondingsurface of the first semiconductor substrate or the second semiconductorsubstrate.
 18. The imaging device of claim 1, wherein a first connectionportion of the plurality of first connection portions and a secondconnection portion of the plurality of second connection portions isdisposed in an area between the pixel section and the signal processingcircuit.
 19. The imaging device of claim 1, wherein an insulatinginterlayer of the first semiconductor substrate contacts an insulatinginterlayer of the second semiconductor substrate.
 20. An electronicapparatus, comprising: an imaging device, including: a firstsemiconductor substrate having a light-incident side and including apixel section, the pixel section including a plurality of photodiodesand at least one of a plurality of transfer transistors, resettransistors, and amplification transistors, a second semiconductorsubstrate having at least a portion of a signal processing circuit,wherein the first semiconductor substrate and the second semiconductorsubstrate are bonded to each other, a first multi-wiring layer formed ata side opposite to the light-incident side of the first semiconductorsubstrate, wherein the first multi-wiring layer is electricallyconnected to the pixel section, a second multi-wiring layer formed at afirst side of the second semiconductor substrate, wherein the sideopposite to the light-incident side of the first semiconductor substrateand the first side of the second semiconductor substrate face eachother, and wherein the signal processing circuit includes at least aplurality of wirings of the second multi-wiring layer and a plurality oftransistors, and an electrode disposed in a peripheral section otherthan the pixel section, wherein the electrode is coupled to a wiring inthe second multi-wiring layer such that the wiring in the secondmulti-wiring layer is electrically connected to an external wiring,wherein, the first multi-wiring layer includes a plurality of firstconnection portions that directly connect to a plurality of secondconnection portions in the second multi-wiring layer, and at least oneconnection portion of the plurality of first connection portions or theplurality of second connection portions is disposed in an areahorizontally located between the pixel section and the electrode; and asignal processing circuit that processes an output signal from theimaging device.